session.h

   1 /*
   2  * Dropbear - a SSH2 server
   3  *
   4  * Copyright (c) 2002,2003 Matt Johnston
   5  * All rights reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE. */
  24
  25 #ifndef _SESSION_H_
  26 #define _SESSION_H_
  27
  28 #include "includes.h"
  29 #include "options.h"
  30 #include "buffer.h"
  31 #include "signkey.h"
  32 #include "kex.h"
  33 #include "auth.h"
  34 #include "channel.h"
  35 #include "queue.h"
  36 #include "listener.h"
  37 #include "packet.h"
  38 #include "tcpfwd.h"
  39 #include "chansession.h"
  40
  41 extern int sessinitdone; /* Is set to 0 somewhere */
  42 extern int exitflag;
  43
  44 void common_session_init(int sock_in, int sock_out);
  45 void session_loop(void(*loophandler)());
  46 void common_session_cleanup();
  47 void session_identification();
  48 void send_msg_ignore();
  49
  50 const char* get_user_shell();
  51 void fill_passwd(const char* username);
  52
  53 /* Server */
  54 void svr_session(int sock, int childpipe);
  55 void svr_dropbear_exit(int exitcode, const char* format, va_list param);
  56 void svr_dropbear_log(int priority, const char* format, va_list param);
  57
  58 /* Client */
  59 void cli_session(int sock_in, int sock_out);
  60 void cli_session_cleanup();
  61 void cleantext(unsigned char* dirtytext);
  62
  63 /* crypto parameters that are stored individually for transmit and receive */
  64 struct key_context_directional {
  65         const struct dropbear_cipher *algo_crypt; /* NULL for none */
  66         const struct dropbear_cipher_mode *crypt_mode;
  67         const struct dropbear_hash *algo_mac; /* NULL for none */
  68         int hash_index; /* lookup for libtomcrypt */
  69         char algo_comp; /* compression */
  70 #ifndef DISABLE_ZLIB
  71         z_streamp zstream;
  72 #endif
  73         /* actual keys */
  74         union {
  75                 symmetric_CBC cbc;
  76 #ifdef DROPBEAR_ENABLE_CTR_MODE
  77                 symmetric_CTR ctr;
  78 #endif
  79         } cipher_state;
  80         unsigned char mackey[MAX_MAC_KEY];
  81 };
  82
  83 struct key_context {
  84
  85         struct key_context_directional recv;
  86         struct key_context_directional trans;
  87
  88         char algo_kex;
  89         char algo_hostkey;
  90
  91         int allow_compress; /* whether compression has started (useful in
  92                                                         zlib@openssh.com delayed compression case) */
  93 };
  94
  95 struct packetlist;
  96 struct packetlist {
  97         struct packetlist *next;
  98         buffer * payload;
  99 };
 100
 101 struct sshsession {
 102
 103         /* Is it a client or server? */
 104         unsigned char isserver;
 105
 106         time_t connect_time; /* time the connection was established
 107                                                         (cleared after auth once we're not
 108                                                         respecting AUTH_TIMEOUT any more) */
 109
 110         int sock_in;
 111         int sock_out;
 112
 113         unsigned char *remoteident;
 114
 115         int maxfd; /* the maximum file descriptor to check with select() */
 116
 117
 118         /* Packet buffers/values etc */
 119         buffer *writepayload; /* Unencrypted payload to write - this is used
 120                                                          throughout the code, as handlers fill out this
 121                                                          buffer with the packet to send. */
 122         struct Queue writequeue; /* A queue of encrypted packets to send */
 123         buffer *readbuf; /* From the wire, decrypted in-place */
 124         buffer *payload; /* Post-decompression, the actual SSH packet */
 125         unsigned int transseq, recvseq; /* Sequence IDs */
 126
 127         /* Packet-handling flags */
 128         const packettype * packettypes; /* Packet handler mappings for this
 129                                                                                 session, see process-packet.c */
 130
 131         unsigned dataallowed : 1; /* whether we can send data packets or we are in
 132                                                                  the middle of a KEX or something */
 133
 134         unsigned char requirenext; /* byte indicating what packet we require next,
 135                                                                 or 0x00 for any */
 136
 137         unsigned char ignorenext; /* whether to ignore the next packet,
 138                                                                  used for kex_follows stuff */
 139
 140         unsigned char lastpacket; /* What the last received packet type was */
 141
 142         int signal_pipe[2]; /* stores endpoints of a self-pipe used for
 143                                                    race-free signal handling */
 144
 145         time_t last_trx_packet_time; /* time of the last packet transmission, for
 146                                                         keepalive purposes */
 147
 148         time_t last_packet_time; /* time of the last packet transmission or receive, for
 149                                                                 idle timeout purposes */
 150
 151
 152         /* KEX/encryption related */
 153         struct KEXState kexstate;
 154         struct key_context *keys;
 155         struct key_context *newkeys;
 156         unsigned char *session_id; /* this is the hash from the first kex */
 157         /* The below are used temorarily during kex, are freed after use */
 158         mp_int * dh_K; /* SSH_MSG_KEXDH_REPLY and sending SSH_MSH_NEWKEYS */
 159         unsigned char hash[SHA1_HASH_SIZE]; /* the hash*/
 160         buffer* kexhashbuf; /* session hash buffer calculated from various packets*/
 161         buffer* transkexinit; /* the kexinit packet we send should be kept so we
 162                                                          can add it to the hash when generating keys */
 163
 164         /* Enables/disables compression */
 165         algo_type *compress_algos;
 166
 167         /* a list of queued replies that should be sent after a KEX has
 168            concluded (ie, while dataallowed was unset)*/
 169         struct packetlist *reply_queue_head, *reply_queue_tail;
 170
 171         algo_type*(*buf_match_algo)(buffer*buf, algo_type localalgos[],
 172                         int *goodguess); /* The function to use to choose which algorithm
 173                                                                 to use from the ones presented by the remote
 174                                                                 side. Is specific to the client/server mode,
 175                                                                 hence the function-pointer callback.*/
 176
 177         void(*remoteclosed)(); /* A callback to handle closure of the
 178                                                                           remote connection */
 179
 180
 181         struct AuthState authstate; /* Common amongst client and server, since most
 182                                                                    struct elements are common */
 183
 184         /* Channel related */
 185         struct Channel ** channels; /* these pointers may be null */
 186         unsigned int chansize; /* the number of Channel*s allocated for channels */
 187         unsigned int chancount; /* the number of Channel*s in use */
 188         const struct ChanType **chantypes; /* The valid channel types */
 189
 190
 191         /* TCP forwarding - where manage listeners */
 192         struct Listener ** listeners;
 193         unsigned int listensize;
 194
 195         /* Whether to allow binding to privileged ports (<1024). This doesn't
 196          * really belong here, but nowhere else fits nicely */
 197         int allowprivport;
 198
 199 };
 200
 201 struct serversession {
 202
 203         /* Server specific options */
 204         int childpipe; /* kept open until we successfully authenticate */
 205         /* userauth */
 206
 207         struct ChildPid * childpids; /* array of mappings childpid<->channel */
 208         unsigned int childpidsize;
 209
 210         /* Used to avoid a race in the exit returncode handling - see
 211          * svr-chansession.c for details */
 212         struct exitinfo lastexit;
 213
 214         /* The numeric address they connected from, used for logging */
 215         char * addrstring;
 216
 217         /* The resolved remote address, used for lastlog etc */
 218         char *remotehost;
 219
 220 #ifdef __uClinux__
 221         pid_t server_pid;
 222 #endif
 223
 224 };
 225
 226 typedef enum {
 227         KEX_NOTHING,
 228         KEXINIT_RCVD,
 229         KEXDH_INIT_SENT,
 230         KEXDONE
 231 } cli_kex_state;
 232
 233 typedef enum {
 234         STATE_NOTHING,
 235         SERVICE_AUTH_REQ_SENT,
 236         SERVICE_AUTH_ACCEPT_RCVD,
 237         SERVICE_CONN_REQ_SENT,
 238         SERVICE_CONN_ACCEPT_RCVD,
 239         USERAUTH_REQ_SENT,
 240         USERAUTH_FAIL_RCVD,
 241         USERAUTH_SUCCESS_RCVD,
 242         SESSION_RUNNING
 243 } cli_state;
 244
 245 struct clientsession {
 246
 247         mp_int *dh_e, *dh_x; /* Used during KEX */
 248         cli_kex_state kex_state; /* Used for progressing KEX */
 249         cli_state state; /* Used to progress auth/channelsession etc */
 250         unsigned donefirstkex : 1; /* Set when we set sentnewkeys, never reset */
 251
 252         int tty_raw_mode; /* Whether we're in raw mode (and have to clean up) */
 253         struct termios saved_tio;
 254         int stdincopy;
 255         int stdinflags;
 256         int stdoutcopy;
 257         int stdoutflags;
 258         int stderrcopy;
 259         int stderrflags;
 260
 261         int winchange; /* Set to 1 when a windowchange signal happens */
 262
 263         int lastauthtype; /* either AUTH_TYPE_PUBKEY or AUTH_TYPE_PASSWORD,
 264                                                  for the last type of auth we tried */
 265 #ifdef ENABLE_CLI_INTERACT_AUTH
 266         int auth_interact_failed; /* flag whether interactive auth can still
 267                                                                  be used */
 268         int interact_request_received; /* flag whether we've received an
 269                                                                           info request from the server for
 270                                                                           interactive auth.*/
 271 #endif
 272         sign_key *lastprivkey;
 273
 274         int retval; /* What the command exit status was - we emulate it */
 275 #if 0
 276         TODO
 277         struct AgentkeyList *agentkeys; /* Keys to use for public-key auth */
 278 #endif
 279
 280 };
 281
 282 /* Global structs storing the state */
 283 extern struct sshsession ses;
 284
 285 #ifdef DROPBEAR_SERVER
 286 extern struct serversession svr_ses;
 287 #endif /* DROPBEAR_SERVER */
 288
 289 #ifdef DROPBEAR_CLIENT
 290 extern struct clientsession cli_ses;
 291 #endif /* DROPBEAR_CLIENT */
 292
 293 #endif /* _SESSION_H_ */